This invention relates generally to a refueling system and receiver, and more specifically to a dual valve receiver designed to support automatic shutoff fast fill refueling of vehicles without pressurizing the fuel tank.
Large vehicles typically have large fuel tanks ranging up to 1200 gallons and larger, which require fast fill systems to quickly pump a large volume of fuel into these large tanks in order to maintain high work productivity. Refueling receivers commonly work in conjunction with fast fill automatic shutoff nozzles that require tank back pressure build up in order for them to shutoff. In order to use a pressurized refueling system, the fuel tanks have to be structurally designed to withstand internal pressures of up to 10 psi, so that such fuel tanks typically are not appropriate for use in lighter vehicles.
Another current method of refueling involves filling a fuel tank with a release or spill valve which allows excess fuel to spill out of the tank when it is full, indicating to an operator to manually shut off the flow of fuel. However, operators tend to force automatic shutoff nozzles open in order to completely fill pressurized tanks, resulting in frequent fuel spills through an overflow valve or vent. In addition, should a nozzle shut off valve and a tank overflow valve fail at the same time, excessive pressure in the fuel tank can cause the tank to suffer catastrophic failure.
For non-pressurized tank refueling, it has been found that a conventional jet sensor used to sense a fuel level and automatically shut off flow of fuel through a fuel receiver commonly transmits a significant residual hydraulic signal even when the jet sensor is fully submerged in fuel, such as when the fuel tank is completely full, so that it would be desirable to minimize any residual fluid flow signal when the sensor is fully submerged, in order to allow a flow control valve in the fuel receiver to close completely. In addition, non-pressurized refueling systems typically make use of a single signal hose and a hydraulic signal that is controlled by a float valve, so that if the single signal hose is damaged or detached, or if the float valve fails to completely seat, the main fuel flow typically will not shut off and tank overflow can occur. It would therefore be desirable to provide a closed-loop non-pressurized refueling shut off system, so that in the event a signal hose is damaged or detached, the system will fail in a safer condition preventing overfill and over-pressurization of the tank. It would also be desirable to provide a non-pressurized refueling shut off system having a jet sensor with substantially no moving parts, that is less susceptible to wear, and that even if damaged would result in an inability to fill the tank, which is a safer condition than if fuel flow into the tank could not be stopped.
The cost of fuel lost through fuel spills and recent environmental laws make it desirable to avoid fuel spills at refueling stations, so that it would be desirable to provide an automated fuel delivery system for large vehicles which is capable of properly filling fuel tanks and that can avoid the risks of fuel spills and over-pressurization of fuel tanks. The present invention addresses these and other needs.